New leads on Boston bombing point to Dagestan

More evidence is piling up that the province of Dagestan in southern Russia holds some of the mysteries behind the Boston bombing.

Russian agents placed Tamerlan Tsarnaev, the elder Boston bombing suspect, under surveillance during a six-month visit he took to Dagestan last year, according to a new report today from the Associated Press. The AP got the information from a security official that asked to remain anonymous.

It's already known that US forces are trying to figure out if Tsarnaev was indoctrinated by militants during his visit to Dagestan, which is experiencing a major Islamic insurgency. 

More from GlobalPost:  In Dagestan, US blamed for Boston bombing

The AP report comes after Russia's  Novaya Gazeta newspaper reported  that officials became aware of Tsarnaev’s presence in the republic in April 2012, after he attended meetings lead by a recruiter for the Dagestani insurgency.

The report adds that officials suspected possible ties between Tsarnaev and William Plotnikov, a Canadian who had joined the insurgency, and then died in a shootout with counter terrorism forces. 

The date of Plotnikov’s death caught the eye of American investigators,  Time magazine reported, because Tsarnaev went back to the US so quickly afterward that he didn't even wait to pick up his new Russian passport. The passport was the whole reason he claimed to be visiting Russia in the first place.